crown problem or fractured tooth

I had a root canal done on a top right molar (#3) in May. After the root canal, I chewed on my left side only waiting for the temporary to be put on and while wearing the temp. About the time I had the tooth crowned, I kept feeling pressure and a swollen feeling in my gums on the back right side. This led to my jaw joint hurting. For a while, I thought the pain was from eating only on the left side of my mouth (which may have slightly put my right jaw joint out of place). When the pain would not go away, I had the bottom right molar root canaled. The pain did not subside so the endodontist did root canal retreatment through the the crown of molar # 3 and found a missed canal. After this, I still felt the pressure and swollen feeling in the back of my gums on the top right. I then had the top right molar (#2) root canaled. However, the pressure and swelling has still continued. I had 3 root canals on bottom molars and few years ago. They all have crowns and I have never had a problem with them. I am wondering if perheps the crown on the top tooth could be causing this pressure and swollen feeling. The tooth is not tender and does not have cold/hot sensitivity. It only bothers me when I am standing or sitting up, not lying down. When I am stanidng or sitting it feels like all the blood is rushing to it. Is this suggestive of a fracutred tooth (vertical root fracutre)? Or could it be the crown?